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SubjectRe: -tip tree resume fail, bisect to 5bd5a45(x86: Add NX protection for kernel data)

* Lin Ming <ming.m.lin@intel.com> wrote:

> Hi, all
>
> Current -tip tree(92c883a) fail to resume after suspend to mem.
> Bisect to commit 5bd5a45(x86: Add NX protection for kernel data).
>
> commit 5bd5a452662bc37c54fb6828db1a3faf87e6511c
> Author: Matthieu Castet <castet.matthieu@free.fr>
> Date: Tue Nov 16 22:31:26 2010 +0100
>
> x86: Add NX protection for kernel data
>
>
> I did some debug and found the regression is caused by below line.
>
> - set_memory_nx(rodata_start, (end - rodata_start) >> PAGE_SHIFT);
> + set_memory_nx(rodata_start, (kernel_end - rodata_start) >> PAGE_SHIFT);
>
> In my machine,
> rodata_start=0xffffffff81a00000, end=0xffffffff81e00000, kernel_end=0xffffffff82200000
>
> Without this commit, kernel page table dumps
>
> ---[ High Kernel Mapping ]---
> ....
> 0xffffffff81a00000-0xffffffff81c00000 2M ro PSE GLB NX pmd
> 0xffffffff81c00000-0xffffffff81d91000 1604K ro GLB NX pte
> 0xffffffff81d91000-0xffffffff81e00000 444K ro GLB NX pte
> 0xffffffff81e00000-0xffffffff82000000 2M RW PSE GLB x pmd
> 0xffffffff82000000-0xffffffff8200c000 48K RW GLB x pte
> 0xffffffff8200c000-0xffffffff82100000 976K RW GLB x pte
> 0xffffffff82100000-0xffffffff82200000 1M RW GLB x pte
> .....
>
> With this commit, kernel page table dumps
>
> ---[ High Kernel Mapping ]---
> ....
> 0xffffffff81a00000-0xffffffff81c00000 2M ro PSE GLB NX pmd
> 0xffffffff81c00000-0xffffffff81d91000 1604K ro GLB NX pte
> 0xffffffff81d91000-0xffffffff81e00000 444K ro GLB NX pte
> 0xffffffff81e00000-0xffffffff82000000 2M RW PSE GLB NX pmd
> 0xffffffff82000000-0xffffffff8200c000 48K RW GLB NX pte
> 0xffffffff8200c000-0xffffffff82100000 976K RW GLB NX pte
> 0xffffffff82100000-0xffffffff82200000 1M RW GLB NX pte
> .....
>
> The only difference is 0xffffffff81e00000(end) to 0xffffffff82200000(kernel_end) is set to NX.
>
> I guess this range code is used by resume wakeup code. So setting it to NX causes problem.
>
> Any idea?

Yeah, the resume area is a trampoline, it needs to be executable.

Thanks,

Ingo


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